Thermal flow sensors are well-known from the current state of the art. Such sensors are, for example, used to determine the flow velocity of a gas. Since for physical reasons thermal flow sensors also react to thermal characteristics of the gas in which they are used in addition to the flow velocity, an exact or precise determination of the flow velocity is no longer possible when the thermal characteristics of the gas change. Such changes in the thermal characteristics may occur during the measuring operation of a flow sensor if, for example, the composition of a gas mixture or the gas itself changes.
This disadvantage is compensated by a recalibration of the thermal flow sensor used. This is typically done by introducing another sensor that identifies the gas present and/or the composition of the gas mixture instead of the flow velocity in order to thus determine the thermal characteristics of the gas and/or the gas mixture on which the determination of the flow velocity is based. However, for this purpose, as mentioned before, another sensor is required without which a recalibration would be impossible.
Alternatively, a recalibration may be obtained using a special software. The gas present or the composition of the gas mixture must be entered into the software for this purpose. It is therefore a disadvantage that another step from the operating staff, namely, a manual input, is required.